The dragon uses one of the following breath weapons.
Fire Breath. The dragon exhales fire in a 30-foot cone. Each creature in that area must make a DC 17 Dexterity saving throw, taking 55 (10d10) fire damage on a failed save, or half as much damage on a successful one.
Weakening Breath. The dragon exhales gas in a 30-foot cone. Each creature in that area must succeed on a DC 17 Strength saving throw or have disadvantage on Strength-based attack rolls, Strength checks, and Strength saving throws for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.